What material to use for point forming die???

[customcutter]

I've been trying to make a point forming die with 7/8" 4140PH (pre-hardened). IIRC I think it is around 34-35RC, and I've been able to machine it easily on the lathe, mill, or even drill it easily with some cheap chinese HSS drill bits.

The problem I'm having is every time I've made a D-reamer to ream out the step drilled die, I wind up breaking the D-reamer. The first time was my fault, I got in a hurry and forgot to temper it back. However, the last time I did temper it back and still snapped the reamer. The reamer is much harder than the die, but it is not "cutting" properly. I tried applying just a little more pressure and snapped it.

What materials have you used to successfully make point forming dies with? I know Cane Man was looking for Graph-mo, but don't remember what he finally came up with. I'm also thinking the finished die should probably be harder than 35RC?

thanks,
CC

[Cane_man]

you are using hardened steel? i would think that is a big part of your problem right there... you need to work with annealed ~ 90 RB hardness

i think BT uses 4140, Ted Smith used O6, 'martin' on here uses O1, KTN uses D2... they all did the lathe work with the steel in the annealed state!

i ended up using annealed O1 then heat treating, worked well on my Chaicom lathe...

the finished die should be as hard as you can get it like 50-60 RC, but you are also going to temper it as well to get some toughness back into it...

ANNEALED 8-)

[customcutter]

I used to make knives, to me 35RC is not hard.:-) I'm used to 58-62RC. Even the cheap chinese HSS drill bits cut through this stuff like butter. However, I am tired of wasting half a day making reamer, and snapping it in 15 minutes. So I'll start looking up some info on how to anneal the 4140PH.

[sprinkintime]

I've been trying to make a point forming die with 7/8" 4140PH (pre-hardened). IIRC I think it is around 34-35RC, and I've been able to machine it easily on the lathe, mill, or even drill it easily with some cheap chinese HSS drill bits.

The problem I'm having is every time I've made a D-reamer to ream out the step drilled die, I wind up breaking the D-reamer. The first time was my fault, I got in a hurry and forgot to temper it back. However, the last time I did temper it back and still snapped the reamer. The reamer is much harder than the die, but it is not "cutting" properly. I tried applying just a little more pressure and snapped it.

What materials have you used to successfully make point forming dies with? I know Cane Man was looking for Graph-mo, but don't remember what he finally came up with. I'm also thinking the finished die should probably be harder than 35RC?

thanks,
CC

Custom Cutter;
I have been using O-1 tool steel for all my work, Dies and Tooling, when you heat treat your die to the max, then you have to draw them back to say 52Rc and then polish. On your tooling(cutter) heat treat to max and draw back to Rc 54-56. Your Rc36 is way to low for a finish product, great for machining tho. 4340 is another mat. you can use for your dies, but I would stick with tool steel for my cutters. Remember Tool steel needs to be drawn back at a certain degree in temp. to get the right Rc you need.
Sprink

[customcutter]

I finally figured out the problem with the D-reamer. I didn't have any relief on the back side of the cutting edge, so it couldn't contact the work in order to cut it.

Sprink,
I agree that 34-35RC is not hard enough for a finished point forming die. However, I don't have any thing else on hand except for W-1. I think I'll make the main body from the 4140PH and make an insert out of W-1. Ream it to .220, harden it, temper it back slightly then lap it out to .224.

thanks,
CC

[sprinkintime]

Customcutter;
Since you have W-1, there is no problem with that tool steel, it a basic all around tool steel, for hardening, heat to 1400-1550 and Quench in water go right back into your oven,kiln or what ever you have and re-heat to about 500 degrees for about a hr. then let it cool down at about 40 degrees per hr. that should bring you to about 55 Rc. If you have a chance to pick-up a little bit of w-2 its has vanadium in it, a little more stable and a finer grain structure. I hope any of this helps you just a little bit.

Sprink

[Cane_man]

cc, mcmaster has O1 and ships same day usually, i think a 3' stick of 1/2" is around $12 before shipping...

[customcutter]

Sprink, Cane,

thanks guys. I think for now I'm going to stick with what I have. The W-1 should work, and I have it in several sizes from 1/4 to 3/4, just no 7/8. So I'll probably just drill &tap the 4140PH and make an insert out of W-1, do all the machining get it close to size heat treat then lap. Sounds so easy I'm suprised it's not done already.:D

[Cane_man]

making the inserts and dropping them into your threaded die body is the only way to go, imo... makes mistakes not so costly [smilie=b:

[sprinkintime]

making the inserts and dropping them into your threaded die body is the only way to go, imo... makes mistakes not so costly [smilie=b:

Customcutter; I love making the insert to fit in the die body, that way if you go oversize you just make another insert, I'm not sure if Corbin's 224 dies are still that way, but that is the way he used to make them, I also do it on my 308 dies.
Sprink

[Twmaster]

Are you threading the inserts into the body or press fit?

Thanks.

[customcutter]

For the de-rimming die I used a drill bushing with a head and a press fit. For the other dies I am going to make them threaded. That way if needed I have more "adjustment" if needed. Especially with the core seating die. I haven't sat down and figured exactly the length of the punch the amount needed to keep the core and jacket in the bottom section, how long to make the "oversized" section of the punch so that it can top out and press against the top of the die, plus how much is needed to extend out the top to tap the core back out.

[sprinkintime]

Are you threading the inserts into the body or press fit?

Thanks.
I thread the body and insert that way only make one body but lots of inserts of different size bullets to fit, about .308 is getting about max. for this method unless you go to 1 1/2- 12 adaptor for you press and dies.
Sprink

[Twmaster]

Thank you.